Continuous coking apparatus



ay 13, 1969 SCHMEUNG ET AL 3,444,048

CONTINUOUS GOKING'APPARATUS Filed Jan. 19, 1967 6 8 r0 a ad era V n 6104 ff khan United States Patent O Int. Cl. Cb 19/04, 1/04 US. Cl.202-121 14 Claims ABSTRACT OF THE DISCLOSURE An apparatus for cokingcoal briquettes and the like by means of finely particulate solid heatexchange material moving in a closed cycle wherein a mixture of thematerial to be coked and of hot heat exchange material is formed in theupper portion of an upright shaft so that coking is carried out duringdownward movement of the mixture through the shaft, the coked briquettesor the like are separated from the particulate, now somewhat cooled heatexchange material and the separated heat exchange material ispneumatically conveyed to the upper portion of the shaft by means of ahot conveying gas so that during movement of the particulate heatexchange material towards the upper portion of the shaft, the heatexchange material is again heated in contact with the hot conveying gas.

BACKGROUND OF THE INVENTION It is known to produce coke briquettes byforming briquettes of coal and a binder such as pitch or sulfite wasteliquors and thereafter coking the thus-forming briquettes inconventional coke ovens. To produce coke in conventional coke ovensrequires between about 15 and hours and for this reason, the yield perunit of coke oven volume is relatively low.

The present invention proposes a more efliective ap paratus for thecontinuous coking of shaped bodies.

According to the present invention, continuous coking of shaped bodiesadapted to be coked, particularly coal briquettes in contact with solidparticulate heat exchange material is to be carried out in a technicallysimple and economical manner and within a very short period of time soas to give a high yield per unit of apparatus volume.

SUMMARY OF THE INVENTION According to the present invention, theeffective continuous coking is achieved in an apparatus for thecontinuous coking of shaped bodies of a first material by contact withthe hot second material consisting of particles substantially smallerthan the shaped bodies of first material, whereby the apparatuscomprises an upright shaft having an upper and a lower portion spacedfrom each other by an intermediate shaft portion, first and secondintroducing means communicating with the upper portion for respectivelyintroducing the first and second material into the upper shaft portionso as to form therein a mixture which will fill the shaft up to apredetermined level, withdrawing means communicating with the lower endportion of the shaft for withdrawing successive quantities of themixture of now coked first material and somewhat cooled second materialtherefrom, which withdrawing means include first treating means forloosening the withdrawn mixture and second treating means for separatingthe second material from the thus loosened mixture. The separated secondmaterial passes then into fiuidizing means which communicate with theabove-mentioned second treating means, wherein a fluidized bed having apredetermined upper level is formed of the separated second material.Furthermore, conveying means are provided which include conduit meanscommunicating with the second introducing means in the zone of the upperend of the shaft and also communicating with the fiuidizing means in thezone of the fluidized bed therein, for passing hot gas therethrough inthe direction from the fiuidizing means towards the second introductionmeans so that the passage of the hot gas through the conduit means willcause at the point of communication between the conduit means and thefiuidizing means suction which will draw fluidized second material fromthe fluidized bed into the conduit means and will convey the fiuidizedmaterial in the conduit means to the second introduction means. Duringpassage of the second material through the conduit means in contact withthe hot gas, the second material will be again heated to a temperaturesufficiently high so that the second material upon reaching the secondintroducing means and being from there introduced into the upper portionof the shaft is capable of supplying the heat required for coking thefirst material which also is introduced into the upper portion of theshaft.

The novel features which are considered as characteristic for theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together with additional objects and advantages thereof, willbe best understood from the following description of specificembodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING The drawing is a schematic elevationalview of an em- DESCRIPTION OF THE PREFERRED EMBODIMENTS According to thepresent invention, the continuous coking is carried out in a reactor orshaft into the upper end portion of which the shaped bodies which are tobe coked and the particulate heat exchange material are introduced sothat a mixture consisting of the shaped bodies embedded in theparticulate hot heat exchange material passes downwardly through theshaft whereby the shaped bodies are coked by being exposed to the hotheat exchange material.

At the lower portion of the shaft, the thus produced hot shaped cokebodies are separated from the particulate heat exchange material andthen cooled, preferably with utilization of the sensible heat of thecoke bodies. The particulate heat exchange material which has beencooled during downward passage through the shaft is then pneumaticallyrecycled for introduction into the upper portion of the shaft, utilizingas conveying fluid a hot gas so that during the recycling theparticulate heat exchange material is again heated to coking temperatureby withdrawing heat from the hot conveying gas.

Certain difiiculties arise by broadly proceeding as described above,which difficulties are overcome by the specific structural features ofthe apparatus of the present invention.

One of the major difiiculties will be found in forming in the upperportion of the shaft a uniform mixture of the shaped bodies and theparticulate heat exchange material. Mechanical mixing devices generallyare unreliable due to the high prevailing temperatures and subject tofrequent breakdowns. In view thereof, according to a preferredembodiment of the present invention, fluidization of the upper portionof the mixture of shaped bodies and particulate heat exchange materialis accomplished in the upper portion of the reactor or shaft. Forinstance, steam may be blown into the mixing zone of the shaft. Therebyit is accomplished that the shaped bodies irrespective of the manner inwhich they are introduced into the upper shaft portion will be evenlydistributed throughout the entire cross-section of the shaft.

Fluidization may be further enhanced by suitable control of thecross-sectional dimensions of the reactor corresponding to the speed offormation of distillation gases upon contact of the coal briquettes orthe like with the hot heat exchange material and suitable proportioningof shaped bodies to be coked relative to hot particulate heat exchangematerial.

Furthermore, difficulties arise with respect to the withdrawal of themixture of heat exchange materialiand shaped coke bodies from the lowerportion of the shaft and with respect to separation of the heat exchangematerial from the withdrawn mixture. Here again mechanical devices tendto break down frequently. In view thereof, according to a furtherembodiment of the present invention, the apparatus is provided withmeans for injecting into the mixture withdrawn from the lower portion ofthe shaft gas in a shock-like manner so as to loosen the mixture and toconvey the loosened mixture pneumatically over an overflow weir followedby separating of the mixture into shaped coke bodies and particulateheat exchange material by passage of the mixture across one or moreinclined screens or grates, broadly referred to herein as screeningmeans.

Furthermore, the fluid tight conveying of the separated particulate heatexchange material into the pneumatic conveying conduit for recycling isconnected with ditficulties which conventionally can be overcome only byinterposition of a sluicing arrangement. This, however, considerablyenlarges the size of the apparatus and involves additional costs.

According to another preferred embodiment of the present invention, theparticulate heat exchange material separated from the mixture by passagethrough the screen ing means is introduced into a fluidizing deviceforming therein a fluidized bed and is then pneumatically introducedinto the conduit leading towards the upper portion of the shaft. Inorder to overcome the pressure increase between the shaft and therecycling conduit, it is preferred to convey the particulate materialfrom the free space below the screening means into the fluidized beddevice with interposition of one or more immersion tubes in which, likein a barometric tube, the particulate material will rise automaticallyto a height corresponding to the pressure differential between the freespace below the screening means and the fluidized bed.

Finally, the reheating of the particulate heat exchange materialfrequently is connected with substantial difficulties. If the conveyinggas which also serves to heat the particulate heat exchange material isexclusively heated in a combustion chamber, it is not possible tocontrol the temperatures and particularly the maximum temperature of theconveying gas with the desired degree of accuracy.

In view thereof, according to a further embodiment of the presentinvention, the particulate heat exchange material while being conveyedin the gas conduit towards the upper portion of the shaft may be furtherheated with gases which are introduced through suitable gas conduitscommunicating with the conveying conduit upstream of the fluidized bedand preferably located closer to the fluidized bed than to the devicefor introducing the particulate material into the upper portion of theshaft. Furthermore, by introducing oxygen-containing gas into therecycling conduit, it will also be achieved that finely subdivided coalparticles which may be carried along with the particulate heat exchangematerial will be subjected to combustion and thereby eliminated withproduction of additional heat.

Referring now to the drawing, a shaft or reactor 1 is shown, in which amixture 2 of shaped bodies which are to be coked and of a particulateheat exchange material the individual particles of which aresubstantially smaller than the shaped bodies, moves downwardly from theupper portion of the shaft towards the lower portion thereof.

The diameter of the shaft is so chosen that the coking gases freed uponcontact between the shaped bodies and the hot particulate heat exchangematerial will tend to fiuidize the uppermost portion of mixture 2 and tocause thereby a more even distribution of the shaped bodies in theparticulate material. This also requires a control of the ratio ofshaped bodies relative to heat exchange material, which ratio willdepend on the proportion of volatilizable material in the shaped bodies.

In addition, preferably, gas inlet conduits 3 are provided forintroducing gas, for instance steam, into the reactor in the zone of theupper portion of the mixture thereof in order to cause or facilitatefluidization.

It is achieved thereby, that the shaped bodies, in the upper portion ofthe shaft will float and thereby will be evenly distributed over theentire cross-section of the shaft and this in turn will result in thecenter and lower portion of the shaft in a mixture consisting of theparticulate heat exchange material hiving the shaped bodies uniformlyembedded therein or distributed therethrough.

Withdrawal of the mixture of now coked shaped bodies and cooledparticulate heat exchange material from the lower portion of the shaftis accomplished by pneumatic means. The mixture flows into chambers 4which at their inclined lower end portions are provided with gasconduits 5. Gas conduits 5 preferably communicate with chambers 4through nozzle through which gas is introduced into chambers 4 inintermittent shocks. Each shock will cause a portion of the mixture toflow over overflow weir 6 onto grate or screen 7. The number of shocksper unit of time and the amount of gas per shock will control the amountof mixture which per unit of time will be withdrawn across the overflowweir. Preferably a plurality of such dosing devices or chambers 4 arearranged communicating with the bottom portion of the shaft sinceotherwise it would be diflicult to achieve a uniform downward movementof the mixture through the coking shaft.

The particulate heat exchange material passes through the openings inscreening means 7 and flows into im-mersion tube 8 which acts as abarometric tube or like a siphon trap. The shaped coke bodies pass alongthe upper face of inclined screening means 7 into cooling shaft orreceptacle 9. The shaped coke bodies are then withdrawn from the lowerportion of receptacle 9 at a temperature of only about 200 C. by meansof a mechanically operated conventional discharge device 10. Cooling ofthe coke in receptacle 9 may be carried out by circulating a gas betweencoke-filled receptacle '9 and indirect heat exchanger 11 whereby in thelatter a part of the sensible heat of the circulating gas is transferredto steam or air which is to be preheated.

The particulate material passing through the openings in screening means7 drops into tube '8 which extends into thev fluidized bed located influidizing device 12. Fluidizing device 12 is provided in conventionalmanner with a false perforated bottom through which gas, for instancepreheated air is introduced in such a manner as to form at the upperface of the perforated bottom a fluidizer layer of the particulatematerial.

The fluidized layer communicates with conveying conduit 14 passiingthrough the fluidizing device, at openings 13 of conveying conduit 14'which openings are arranged in the zone of the fluidized bed, preferablyin the zone of the upper level thereof.

Pneumatic conveying conduit 14 communicates upstream of the fluidizingdevice with combustion chamber 15 in which preheated air is reacted witha gaseous, liquid or solid fuel in such proportions that the gas passingfrom combustion chamber 15 into conveying conduit 14 still contains freeoxygen. This will prevent excessive temperature peaks in the conveyinggas. Preferably, the temperature of the flue gases which are introducedfrom combustion chamber into conveying conduit 14 will be several 100 C.higher than the temperature of the particulate material of the fluidizedbed.

The free oxygen remaining in the combustion gas will serve for burningsmall coke particles carried along with the particulate heat exchangematerial so that additional heat is created in conduit 14 and at leastpartially transferred to the particulate material carried along by thegas in conduit 14.

In addition, one or more gas conduits '16 may be provided, communicatingwith conduit 14 upstream of fluidizing device or chamber 12 andpreferably closer to chamber 12 then to the upper portion of shaft 1,for introducing additional fuel for combustion with the free oxygen ofthe gas flowing through conduit 14. The temperature of the gas inconduit 14 should be sufficiently high so that the particulate heatexchange material while passing through conduit 14 is heated to atemperature which is between about 50 and 200 C. above the cokingtemperature required for coking the shaped bodies in shaft 1.

Conduit 14 terminates at its upper end in a separator 17 from which gasescapes through conduit 18, whereas the particulate material carriedalong into separator 17, due to the larger cross-sectional dimensions ofthe latter, will not be carried to conduit 18 but will drop through thefunnel-shaped portion 19 of separator -17 into tubular conduit 20.Tubular conduit 20 extends downwardly into the upper portion of shaft 1so that the lower open end of conduit 20 will be below the upper level24 of the upper fluidized zone of mixture 2.

The gas pressure differential between shaft 1 and separator 17 isovercome by a column of particulate material in conduit 20. This makesit possible to withdraw the heating gas through conduit 18 andseparately therefrom the distillation gases from shaft or reactor 1.

Depending on the type of shaped bodies which are to be coked, forinstance depending on the composition of coal briquettes, it may beadvantageous to preheat the shaped bodies prior to introduction intoshaft '1, or even to subject the shaped bodies to some degree of lowtemperature distillation.

If this is desired, the present invention provides for conduit meansrecycling heat exchange gas from receptacle 9 through conduit 21 intostorage means 22 into which, preferably from above, the shaped bodieswhich are to be coked are introduced. In storage means such as hopper22, the shaped bodies are contacted by the gas which has been heated inreceptacle 9 in contact with the hot shaped coke bodies and thuspartially distilled bodies are then introduced through conduit 23 ontothe upper portion of shaft 1. The gas which has been cooled to someextent while being in contact with shaped bodies in hopper 22 passesthrough conduit 24 to be reintroduced into receptacle 9. Conduit 24includes a condensing device 25 for condensing and separatingcondensible volatilized products formed in hopper 22. Excess gas andvapors which cannot be condensed may be withdrawn through conduit 26.

The following examples are given as illustrative only, without, however,limiting the invention to the specific details of the examples.

Example 1 Egg-shaped briquettes each weighing 24 grams and formed of93.6% fine coal including 9.2% volatile con stituents and 6.4% pitch arecontinuously coked in a reactor such as shaft 1, having an innerdiameter of400 mm. and a height of 4 meters. Sand having a particle sizeof between about 0.2 and 0.5 mm. is used as the particulate heatexchange material. The withdrawal and dosing device 4 communicating withthe bottom portion of reactor 1 has a diameter of 200 mm. and a heightof 400 mm. Every 0.5 second about 0.3 standard cubic liter of gas isshock-like introduced through tube 5,

, '6 thereby causing a portion of the mixture to be transported ontograte 7. The shaped coke bodies rolling downwardly along the upper faceof grate 7 are introduced into a receptacle 9 having a height of 1.2meters and a diameter of 250 mm. Cold inert gas which has been formed byconsumption of the oxygen present in the initially introduced air iscirculated between receptacle 9 and heat exchanger 11.

The thus cooled coke bodies having a temperature of about 150 C. arewithdrawn at 10'.

Immersion tube 8 in which a column of particulate material is formed ofthe sand passing through the openings of grate 7, has an inner diameterof 50 mm., and the fluidized bed device has a length of 50 cm. and awidth of 10 cm. The height of the fluidized sand layer in fluidizingdevice 12 equals about 10 cm.

Conduit 14 for conveying the sand to the introduction device 17 and fromthere to the upper portion of shaft 1 has a width of 130 mm.

Combustion chamber 15 is fed with 150 standard cubic meters of air perhour and with an amount of fuel gas so arranged that the oxygen contentof the gas leaving consumption chamber 15 equals about 7 and 8%.

Additional fuel is introduced into conduit 14 through gas conduit 16 insuch amounts that upon combustion of the additional fuel the combustiongas is substantially free of oxygen.

Separator 17 has a length of 800 mm., a width of 320 mm. and a height of360 mm., and communicates at its lower end portion 19 with pipe 20opening into the upper portion of shaft 1 below the upper level ofmixture 2 therein. Pipe 20 has a diameter of 70 mm.

By processing kg. of shaped coal bodies per hour, between about 0.6 and0.8 metric ton of sand per hour is circulated. The sand is introducedinto shaft 1 at a temperature about 1100 C. and cooled during downwardpassage to the fluidized bed by about C. While passing upwardly throughconduit 14, the thus cooled sand is then again heated to about 1100 C.

The flue gas escaping from separator 17 through conduit 18 is free ofoxygen and combustible constituents. The coal distillation gases whichare withdrawn from the upper portion shaft 1 contain only as muchnitrogen as is generally formed in the pyrolysis of coal. About 22standard cubic meters per hour of coal distillation gases having acalorific value of 4100 kcal. per standard cubic meter are thus producedand recovered completely separated from the flue gases.

Example 2 The inner diameter of reactor or shaft 1 is 1.9 meters and itsheight equals 6 meters. 'Four withdrawal chambers 4 each having adiameter of 200 mm. and a height of 800 mm. communicate with the lowerportion of shaft 1. The withdrawal chambers are rhythmically succesivelycharged with gas portions of about 2 standard cubic liters each. Onesuccessive charging of the four chambers requires 5 seconds. The mixtureis transferred over the overflow weir of all chambers onto a singleinclined screen means 7 from which the shaped coke bodies roll into acooling receptacle 9 having a diameter of 1.2 meters and a height of 2.5meters and wherein the coke bodies are cooled in contact withcirculating inert gas to a temperature of about C.

The immersion tube 8 through which the particulate heat exchangematerial, sand of particle sizes between 0.2 and 0.5 mm. flows into thefluidizing device or trough 12 has a rectangular cross-section of 20 x40 cm. Trough 12 has a width of 40 cm. and its length is 2 meters. Thefluidized layer or bed formed therein has a height of 30 cm.

Conduit 14 has a diameter of 560 mm. and is charged with 2700 standardcubic meters per hour of flue gases which are free of molecular oxygen.The flue gas is produced in combustion chamber 15 by introducing intothe same the entire required amount of air but only about two-thirds ofthe required amount of fuel gas. The remaining portion of the requiredfuel gas is introduced into conduit 14 through gas conduit 16.

The separation chamber 17 at the upper end of conduit 14 has a width of1 meter, a height of 1.75 meters and a length of 2 meters. Chamber 17terminates downwardly into a funnel-shaped receptacle 19 which againterminater at its lower end in a tube 20 having a width of 200 mm. andextending downwardly into the upper portion of shaft 1 below the upperlevel of the fluidized upper portion of mixture 2.

The yield of the presently described coking apparatus equals about 5metric tons of shaped coke per hour, requiring an hourly sandcirculation of 40 metric tons. The temperature of the sand at the pointof introduction into shaft 1 is 1100 C., and the temperature of themixture being withdrawn from the lower end portion of shaft 1 is about980 C.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofcoking devices differing from the type described above.

While the invention has been illustrated and described as embodied in acontinuous coking apparatus wherein shaped bodies are coked in contactwith a hot solid finely particulate heat exchange material, it is notintended to be limited to the details shown, since various modificationsand structural changes may be made without departing in any way from thespirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can by applying current knowledgereadily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this inventionand, therefore, such adaptations should and are intended to becomprehended within the meaning and range of equivalence of thefollowing claims.

What is claimed as new and desired to be protected by Letters Patent isset forth in the appended claims.

We claim:

1. In an apparatus for continuously coking shaped bodies of a firstmaterial by contact with a hot second material consisting of particlessubstantially smaller than said bodies, in combination,

(A) upright coking means (1) having an upper and a lower portion, fordownwardly passing therethrough an intimate mixture of said first andsecond materials, so as to coke during such passage said first materialwith said second material; and

(B) withdrawing means (4, 5, 6, 7) arranged below and communicating withsaid lower portion of said upright coking means for withdrawing from thelatter successive quantities of said mixture, said withdrawing meansincluding loosening means (4, 5, 6) for loosening the withdrawn mixtureand also including separating means (7) located downstream of saidloosening means for separating thus-loosened mixture into one fractionconsisting essentially of said first material and another fractionconsisting essentially of said second material, said withdrawing meanscomprising at least one inclined chamber (4) having an upper and a lowerportion and communicating at its lower portion with the lower portion ofsaid coking means, the upper portion of said chamber (4) defining anoverflow Weir (6), and said loosening means comprising blower means (5)communicating with the lower portion of chamber (4) for introducing gasinto the lower portion of chamber (4) below the level of weir (6), sothat quantities of said mixture introduced from the lower portion ofsaid coking means into the lower portion of chamber (4) will be causedby the thus introduced gas to flow upwardly in said inclined chamber andover weir (6) towards said separating means (7) and thereby to beloosened prior to being separated into said fractions.

2. An apparatus as defined in claim 1, and including (C) first (22, 23)and second (17, 19, 20) introducing means communicating with said upperportion of said coking means (1) for respectively introducing said firstand said second material thereinto so as to form a mixture (2) fillingsaid coking means (1) to a predetermined level (24);

(D) fluidizing means (12) located downstream of and communicating withsaid separating means (7) for receiving the separated second materialand fluidizing the same so as to form thereof a fluidized bed having apredetermined upper level; and

(E) conveying means including conduit means (14) located outside saidcoking means (1) communicating with said fluidizing means (12) in thezone of the fluidized bed therein, and also communicating with saidsecond introducing means (17) for passing hot gas therethrough in thedirection from -said fiuidizing means (12) towards said secondintroduction means (17) to thereby cause suction at the point ofcommunication (13) of said conduit means with said fiuidiz-ing means soas to draw fluidized second material from said fluidized bed (12) and toconvey the same to said second introduction means '(17), simultaneouslyheating said second material by contact with said hot gas so that thusheated second material will pass from conduit means (14) into saidsecond introducing means (17) and from there into said upper portion ofsaid coking means (1) to forum therein a mixture (2) with said firstmaterial.

3. An apparatus as defined in claim 2, wherein said first introductionmeans (23) communicates with said coking means (1) at a level above thelevel of communication between said second introduction means (20) andcoking means (1).

4. An apparatus as defined in claim 3, wherein said second introductionmeans (20) communicates with said coking means (1) below saidpredetermined level (24).

5. An apparatus as defined in claim 2, wherein said conduit means (14)communicates with said fluidizing means (12) in the zone of the upperlevel (13) of said fluidized bed.

6. An apparatus as defined in claim 2, wherein said separating meansincludes screening means (7) arranged downstream and below the level ofsaid weir (6) for separating from said loosened mixture second materialpassing through said screening means (7 into said fiuidizing means (12),said first material being incapable of passing through said screeningmeans.

7. An apparatus as defined in claim 6, wherein said screening meansincludes a downward inclined screen (7 for passing said first materialalong the upper inclined face thereof by force of gravity.

8. An apparatus as defined in claim 7, and including heat exchange meansoperatively associated with the lower end portion of said inclinedscreen (7), said heat exchange means including a receptacle (9) forreceiving first material from screen (7), and gas circulating means forcirculating a gas between said receptacle (9) and an indirect heatexchanger (11) so as to heat said gas in said receptacle in contact withthe relatively hot first material, and to give up a portion of thesensible heat of the thus heated gas during passage thereof through saidheat exchanger (11).

9. An apparatus as defined in claim 7, and including a receptacle (9)associated with the downstream end portion of said inclined screen forreceiving first material from said screen, and wherein said firstintroduction means includes storage means (22) for storing firstmaterial prior to introduction of the same into said shaft; andincluding second conduit means (21) for passing gas through saidreceptacle (9) so as to heat the same in contact with the relatively hotfirst material therein, and for passing the thus heated gas through saidstorage means (22) so as to preheat first material therein prior tointroduction of the latter into said coking means (1).

10. An apparatus as defined in claim 9, wherein said storage meanscomprises a hopper (22) having an upper and a lower portion andincluding inlet means for said first material in the upper portion andoutlet means (23) in the lower portion of said hopper, said outlet meanscommunicating with coking means (1).

11. An apparatus as defined in claim 10, and including third conduitmeans (24) communicating with said storage means (22) and saidreceptacle (9) for passing gas, which has been cooled in said storagemeans (22) in contact with first material, from said storage means tosaid receptacle, said third conduit means including condensing means(25) for condensing and separating from said gas condensableconstituents thereof formed by contact of hot gas with said firstmaterial in said storage means.

12. An apparatus as defined in claim 3, and including first gasintroducing means (3) communicating with the upper portion of saidcoking means (1) below the level of communication between said secondintroduction means (20) and said treating means (1) for introduction ofgas into the latter so as to fluidize the mixture of first and secondmaterial located in the zone of the level of communication between saidfirst gas introducing means and said treating means.

13. An apparatus as defined in claim 6, wherein said separating meansincludes conduit means (8) extending from below said screening meansinto said fiuidizing means (12) below said predetermined upper level ofsaid fluidized bed for passing separated second material from saidseparating means into said fiuidizing means.

14. An apparatus as defined in claim 2, and including second gasintroducing means (16) communicating with said conduit means (14)upstream of said fiuidizing means (12) and farther distant from saidsecond introduction means (17, 19, 20) than from said fiuidizing means(12) for introducing additional gaseous fuel into said conduit means forcombustion therein so as to raise the temperature of the gas flowingthrough conduit means (14) towards second introduction means (17, 19,20) into said conduit means.

References Cited UNITED STATES PATENTS 2,131,702 9/1938 Berry 201-62,480,670 8/1949 Peck 201-28 2,741,549 4/1956 Russell 201-31 2,743,2164/1956 Jahnig et al. 201-12 2,879,208 3/1959 Brice 201-31 2,984,6025/1961 Nevens et a1. 201-12 3,117,064 1/ 1964 Friedrich 201-12 3,140,2407/1964 Fowler 201-12 FOREIGN PATENTS 1,135,419 8/1962 Germany.

WILBUR L. BASCOMBE, JR., Primary Examiner.

US. Cl. X.R.

